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Python CPU Feature Detection

Project description


Prototype of replacement for for high-performance Python modules. Detects CPU features such as:

  • SIMD instruction support
  • Number of cores (both virtual and physical)
  • Cache sizes

It is fast, with an import+execution time of ~1 ms

It is written in C99. It supports Windows with MSVC and Linux with GCC/LLVM compilers. MacOSX should also work with GCC/LLVM but has not been tested.

It is licensed under Creative Commons Zero, so it may be freely incorporated as a submodule into your own projects.

It needs to be tested on a variety of machines.


The module generates a dict called CPUFeature on import which contains useful information regarding optimization and compilation for the host. For my Intel i7-7820X Skylake CPU, it generates the following info:

> python -c "import cpufeature; cpufeature.print_features()"

=== CPU FEATURES === VendorId : GenuineIntel num_virtual_cores : 16 num_physical_cores : 8 num_threads_per_core : 2 num_cpus : 1 cache_line_size : 64 cache_L1_size : 32768 cache_L2_size : 1048576 cache_L3_size : 11534336 OS_x64 : True OS_AVX : True OS_AVX512 : True MMX : True x64 : True ABM : True RDRAND : True BMI1 : True BMI2 : True ADX : True PREFETCHWT1 : False MPX : True SSE : True SSE2 : True SSE3 : True SSSE3 : True SSE4.1 : True SSE4.2 : True SSE4.a : False AES : True SHA : False AVX : True XOP : False FMA3 : True FMA4 : False AVX2 : True AVX512f : True AVX512pf : False AVX512er : False AVX512cd : True AVX512vl : True AVX512bw : True AVX512dq : True AVX512ifma : False AVX512vbmi : False

Notes on Fields

  • If num_threads_per_core > 1 likely Intel Hyperthreading (or equivalent architecture) is present. The physical core count may be unreliable in virtual environments.
  • Cache sizes are in bytes.
  • For AVX2, check AVX2 and OS_AVX2.
  • For AVX512, check AVX512f and OS_AVX512. Python support for AVX512 instructions is highly limited outside of compilation with ICC. MSVC does not have AVX512 support until MSVC2017.


  • Based on FeatureDetector by Alexander Yee (
  • Ported to Python by Robert A. McLeod, who added detection of cores, and cache sizes.
  • drfinkus contributed to AMD support.
  • WidgetA contributed support for compilation with Clang.

Release Notes


  • Added support for AMD processors.
  • Added a script for valgrind to more easier locate problems when the module crashes.


  • Fixes for compilation with clang.


  • Added detection of processors, cores, and cache sizes
  • Created Python wrapper around FeatureDetector
  • Reduced FeatureDetector to C99 for better cross-platform compatibility

Project details

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